The eighth in the "Today's Instrument" series of Wii Music demonstration videos is one of the most iconic, recognizable instruments, and one that is the source of a lot of people's issues with Wii Music: the electric guitar. As we all know, in Guitar Hero you push buttons on a plastic guitar controller in time with musical cues. In Wii Music, you do this.
Perhaps if this one instrument weren't in the game, people wouldn't be as inclined to compare the two and judge Wii Music so harshly, since aside from the musical theme and the idea of simulating instruments, they're extremely different things? More likely they'd complain about the lack of electric guitar.
[Video uploaded by Balance Board Blog]